Experimental studies with laboratory animals have shown that behaviorally-induced hypoventilatory breathing potentiates the hypertensinogenic effects of high sodium intake. Current studies in this project focus on the interactions of pCO-2, sodium intake and blood pressure in humans. One experimental study investigates the correlation that exists between resting pCO-2 and (a) higher ambulatory blood pressure in the natural environment, and (b) the magnitude of pressor response during laboratory role playing of social conflict. A study in progress also investigates blood pressure sensitivity to high sodium intake as a function of resting pCO-2.